The invention is based on an electrically controlled fuel injector for fuel injection in internal combustion engines, as defined hereinafter.
In a unit fuel injector of this generic type (German Offenlegungsschrift 35 21 426), the control valve is embodied as a ring valve and together with the electric control magnet is disposed coaxially around the injection pump and the pump work chamber. Although this produces good control forces, it also involves relatively large radial minimum dimensions and above all a relatively high number of high-pressure sealing faces, which must be very well machined if the necessary tightness is to be achieved.
In another known unit fuel injector of this type (European Patent Reference 0 174 718), the control valve and the control magnet are distributed axially over a relatively long portion of the unit fuel injector housing, which especially presents the problem of a large number of abutment points of the high-pressure conduit, each of which must be very well machined and sealed off, since any leak, however slight, falsifies the already predetermined injection quantity. Assembling the unit fuel injector also entails considerable effort, especially to coordinate the rotational position of the various parts so as to assure that the inlet and outlets of the various conduit segments are covered. Modern high-rpm engines require a very high switching frequency of these electrically controlled unit fuel injectors; even slight control errors in the injection quantity produce a considerable drop in engine efficiency and above all make for poorer emissions.